Mixtures of low melting glycols in wide composition ranges which include their eutectic point are made to either retain fluidity during normal materials storage or to retain fluidity rapidly upon return of the material to room temperature by the addition of small to moderate amounts of water. These liquid forms provide distinct advantages over storage of the solid forms of these mixtures to users for polycondensation reactions.
The physical handling of low melting solids is often difficult because of their tendency to clump together when stored as a solid. This is especially true for a number of glycols used for the synthesis of polyester polymers. When the requirements for such materials are large, facilities for molten storage of these materials may be justified. The capital required to install and to maintain these facilities is often substantial because heating is required.
A second means of providing a fluid product is available if the material has sufficient water solubility that the addition of a small, fixed amount of water will impart a freezing point that is low enough to permit pumping at ordinary temperatures. Examples of the latter situation include 2,2 dimethyl 1,3 propanediol (NPG Glycol) and 1,4 cyclohexanedimethanol (CHDM) which are routinely mixed with 10 weight percent water to provide fluid materials.
An alternative means of providing low melting glycols in a fluid form has been exemplified in U.S. Pat. No. 4,474,939. This procedure involves the formation of eutectic mixtures of glycols which retain fluidity at or near room temperature. The glycols taught in this patent are NPG Glycol, cyclohexanedimethanol(CHDM), 1,6 hexanediol, and 2,2,4 trimethylpentane 1,3 diol (TMPD). These eutectic mixtures are claimed to offer benefits both in terms of material handling and properties of polyester resins produced therefrom them.
Recently, L.R. Thurman, et al. disclosed in European Patent Application Publication No. 0 410 167 that NPG Glycol also forms a eutectic mixture with 2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl 3 -hydroxypropionate (hydroxypivalyl hydroxypivalate or HPHP). However, this binary mixture, upon cooling to, for example, 0.degree. C., will solidify and will not spontaneously become fluid upon warming to room temperature; the present invention as described below, provides a solution to this problem. The Thurman reference describes a method for producing such mixtures from a by product stream.